JP4965459B2 - Intervertebral prosthesis - Google Patents

Abstract

The prosthetic joint has at least two members having each a cooperating articulating surface layer on a substrate material. At least one of said articulating surface layers comprises amorphous diamond-like carbon; or Titanium Nitrate (TiN) on a bonding layer bonded to the substrate material. The prosthetic joint provides a reduction of the number of wear debris and shows enhanced dry run properties.

Description

Detailed Description of the Invention

  The present invention relates to an intervertebral prosthesis, and more particularly to an intervertebral disc prosthesis.

  In recent years, intervertebral prostheses have gained wide acceptance in spinal surgery. These prostheses are inserted in the intervertebral disc anteriorly or anteroposteriorly of the spine. This implantation technique displays a certain risk and access is directed through the abdominal region. There is a risk that the larger tube in the area of the front waist step will be damaged. Anterior access is disadvantageous from a biomechanical point of view, and the longitudinal ligaments in front of the spine are partially or wholly dissected to allow prosthetic insertion. Anatomy causes some instability of the vertebral body and, in the worst case, promotes the movement of the abdominal prosthesis. In order to reduce the risk of prosthetic movement, anchoring means are used, such as fixing the prosthesis on the adjacent spinal cover plate.

  This type of intervertebral disc prosthesis is known as WO 01/01893, such as Marnai. This known prosthesis has a ball socket connection and includes two different types of projections that are secured to the prosthesis at two vertebrae. It has been proposed to minimize the height of the prosthesis in the document, and the two parts are configured to engage each other and are inserted therein. Despite the provision of anchoring means, there is a prosthetic risk for movement along the insertion channel.

  The present invention is intended to provide a treatment for this. The present invention leads to an intervertebral prosthesis, the purpose of implantation being two parts that can be disassembled and inserted into the intervertebral space via transvertebral foramen and / or access outside the intervertebral foramen. The joint of the intervertebral prosthesis is preferably composed of a spherical cap-like structure and a corresponding spherical recess. In the implantation of two prosthetic elements, it is implanted separately in the intervertebral space via two separate accesses, and the longitudinal axis of the prosthetic element is arranged in the other intervertebral space. By freely selecting the angle α between the longitudinal axes of the two prosthetic elements, the position of the intersecting point can be adjusted in the direction of the arrow with the insertion point being maintained unchanged. This adjustment can be planned by CT or radiographic means prior to surgery and can also be defined during surgery by means of a guide wire and / or mold.

The advantages achieved by the present invention reside within the facts inherently resulting from the intervertebral prosthesis of the present invention.
-Individual adjustments of any combination of spinal intervertebral prostheses are possible. The individual organization of the operating elements can be taken into account.
-The motion sequence of the individual segments is considered before surgery and is characterized by the surgeon.
-Complex and safe surgical techniques are enabled in comparison to implants inserted into fully assembled intervertebral spaces.
-Risk due to movement of the prosthesis forward and backward and / or laterally due to spinal curvature / dilation or lateral flexion is minimized.
-The natural disc must only be partially removed, ie only to reveal two strategies of width B and length H in order to implant two prosthetic elements in the intervertebral space (disc) Only the equivalent surfaces of the two prosthetic elements are in contact with each endplate in the bone. Once the two prosthetic elements are implanted, the remainder of the disc is maintained intact, preventing the intervertebral prosthesis from moving laterally and / or anteriorly and posteriorly.

  In a preferred embodiment, the ratio of height H to width B of the prosthetic element is between 3: 1 and 5: 1. The effect of this design is essentially only to reveal a narrow path of width B and length H in order to implant the two prosthetic elements within the intervertebral space (disc).

  In another embodiment, the intervertebral prosthesis is composed of two parts, ie the cap-like structure is composed of one of the two prosthetic elements and the other part.

  In a further embodiment, the intervertebral prosthesis is composed of three parts, and a cap-like structure formed from the three parts is connectable with one of the two prosthetic elements. The effect of this design is essentially seen in the fact that the plate and the cap-like structure are constructed by using different materials, making it possible to achieve optimal sliding properties for the joint surface. Suitable materials for the plates are titanium or titanium alloys or PEEK or coated variants, and for hat-like structures are highly crosslinked polyethylene (X-UHMWPE) cobalt and chromium alloys or ceramic materials. .

  In yet a further embodiment, the intervertebral prosthesis is constructed of at least three parts and includes an articulating shell that includes a recess that is detachable from the first and second prosthetic elements as a third portion. The effect of this design is essentially seen in the fact that the plate and the cap-like structure are constructed by using different materials, making it possible to achieve optimal sliding properties for the joint surface.

  In a further embodiment, the cap-like structure and the joint shell are composed of a combination of metal and plastic. The effect of this design is that it is possible to use proven combinations of bonding and rearrangement materials, such as highly crosslinked polyethylene (X-UHMWPE) and cobalt and chromium alloys. A further effect is seen in the fact that low friction forces can be achieved due to the associated movement of the joint surface and load compensation of the axial effect can be achieved.

  In another embodiment, it is used for ceramic-to-ceramic joints.

  In a further surface embodiment, the cap-like structure and the surface of the recess are coated with titanium carbide or amorphous carbon (ADLC), substantially reducing the coefficient of friction.

  In another embodiment, at least the cap-like structure is made of a material having an expansion capability (eg, hydrogel).

As another example, the cap-shaped structure is composed of a monomer, a comonomer, a homopolymer, an oligomer, or a hybrid material including a material having fluidity and thermosetting property. Groups a) polyethylene glycol, preferably polyethylene glycol (di) -acrylate b) n-vinyl pyrrolidone c) vinyl, preferably vinyl alcohol d) styrene.

  The resulting polymers can vary widely depending on their elasticity. The effect of this design is due to the reduced volume of the joint, essentially due to the fact that the insertion of the intervertebral prosthesis is less invasive and the increased volume is most suitable for achieving optimal joint function Can be seen.

As a further example, the first prosthetic element is selected from a first kit of first prosthetic elements with at least M ≧ 2, and the second prosthetic element has at least N ≧ 2 Selected from the second kit. The first and second kits are located at different heights and at the centers of the joint ribs or the respective ribs, ie the center of rotation. The following effects are achieved by the means of this embodiment. The following effects are achieved by this embodiment.
-The position of the center of rotation can be adjusted in height when it is arranged in a modular manner with two elements.
-The element can change the radius of the cap-like structure, and the center of rotation of the intervertebral prosthesis can be adjusted.
-The position and angle measurement of the center of rotation and the translational part of the intervertebral prosthesis are freely selected in a relatively wide range, and the translational parts of the prosthetic elements are measured laterally to each other on the central axis of the prosthetic element It is a moving part.
The prosthetic element takes into account the joint requirements of the moving part and makes it possible to include cap-like structures with different radii; The radius of the larger cap-like structure is within the deviation of the higher part of the translational movement, and the patient's spinal flexion increases the pressure on the joint joint and accelerates degeneration.
The height of the prosthetic element and the corresponding radius of the joint cap structure of the intervertebral prosthesis can be deformed and are compatible with the size of the various intervertebral spaces.

An intervertebral disc prosthesis is a method of implanting an intervertebral prosthesis in an intervertebral space,
A) implanting a first prosthetic element via a first access on the central axis of the intervertebral prosthesis next to the intervertebral region;
B) Implanting the second prosthetic element of the intervertebral prosthesis via a second access different from the first access to the central axis of the intervertebral prosthesis and having a width value of B Measured for two prosthetic elements in the transverse direction with respect to the central axis where the height value is H and H> B, the longitudinal axes L ₁ and L _{2 of} the first and second prosthetic elements are at an angle α> 0 Extending a parallel line intersecting the length H in degrees;
C) The second prosthetic element and the first prosthetic element are combined in a well-defined manner during implantation.

  According to a type of embodiment of the method of the present invention, at least one access is placed outside the transvertebral foramen or extravertebral foramen. Transforaminal access is known and established as spinal surgery. For extravertebral access, it is possible to have a large opening toward the disc space without adversely affecting the abdominal or dorsal ligaments or nerve structures.

  As a preferred embodiment, the two accesses are located on the prosthesis.

  As another example, the first access is placed in the transvertebral foramen.

  In still other embodiments, the second access is located outside the intervertebral foramen.

  In addition, in another embodiment, the intervertebral disc located in the space between the two vertebral bodies is such that the all-equal surfaces of the two prosthetic elements designed adjacent on the bone contact each endplate of the vertebral body It is removed to the extent that you do.

In a still further embodiment, each of the two accesses has an input point E, which is spaced from the arrow axis 10 by two implanted prosthetic element longitudinal axes L ₁ and L _2. It arrange | positions so that it may expand in the center in the front-back direction so that angle (alpha) may be formed, and the setting range of angle (alpha) is 25 degree | times to 120 degree | times.

  In the following, the invention and improvements of the present invention are illustrated in greater detail with reference to a partial diagram of an embodiment of an intervertebral prosthesis according to the present invention.

The embodiment shown in FIG. 1 essentially comprises an intervertebral prosthesis 1, which is composed of two prosthetic elements 2, 3 having rectangular equal surfaces 4, 5. The two prosthetic elements 2 and 3 have a height H and a width B, but are releasably connected to each other by means of a joint 14. The joint 14 is composed of a cap-shaped portion 9 and a concave portion 11 corresponding to the cap-shaped portion 9. In this embodiment, the radius of the cap-shaped portion 9 is larger than the width B of the prosthetic element 3, but is lower than the height H of the prosthetic element 3, and the height H is four or five times longer than the width B. Due to this design feature, the slopes of the longitudinal axes L ₁ , L ₂ of the two prosthetic elements 2, 3 as a whole differ in relation to each other, depending on the magnitude of the angle α (where α is The angle α between the longitudinal axes L ₁ and L _{2 in a} plane extending perpendicular to the central axis 6). Optimal joint function is achieved with an angle α at 90 degrees. When the angle is 90 degrees, the inclination angle is twice the size at the angle α at 0 degrees.

The embodiment shown in FIG. 2 includes first and second prosthetic elements 2, 3, which first and second prosthetic elements 2, 3 have longitudinal axes L ₁ , L ₂ and an arrow axis 10. It is. The vertical axis of the two prosthetic elements 2,3 _L 1; _{L 2} has a point of intersection S, to form an angle alpha. An entry point E, which is arranged with respect to the arrow axis 10 and marked as a point to be inserted between the two prosthetic elements 2; 3 in the intervertebral, The distance between is changed to a different angle α formed by the prosthetic axes L ₁ and L ₂ (FIGS. 3 and 4).

The two cross sections shown in FIGS. 3 and 4 include prosthetic elements 2 and 3 on prosthetic axes L ₁ and L _2, respectively. Due to the difference in the angle α caused by the correction of the position of the prosthetic axes L ₁ and L _2, the point S of the cross section is moved along the arrow axis 10 and the point E of the entrance increases without increasing the distance A. Remain. In accordance with the evaluation given in the special material, the deformation shown in FIG. 3 and having a cross-section S-point placed in the back about the center of the end face of the vertebral body is shown in FIG. This is more advantageous than a deformation having a cross-sectional S point.

Description of Surgical Method A surgical method for accepting the implantation of the intervertebral prosthesis 1 will now be described with reference to FIG.

  a) As a prior art of implantation, the intervertebral disc is prepared as required by the size of the prosthetic elements 2,3. Instead of removing all the intervertebral discs, it is only necessary to reveal the two pathways, said 2 so that the two equal surfaces 4, 5 of the intervertebral prosthesis 1 can directly contact the covering plate of the vertebral body. One path is big enough. Due to this effect, the intervertebral space (disc) is removed only in such a range, and the entire application surface of the two prosthetic elements is connected with respect to the endplate. Once the two prosthetic elements 2, 3 are implanted, the remainder of the intervertebral disc remains in place, preventing the intervertebral prosthesis from moving laterally.

b) The injection of the two prosthetic elements 2,3 is then performed via the two posterior lateral fusion access 12,13 for the preparation of the two injection tubes in the disc. It is preferred that as soon as a first set of prosthetic elements 2, 3 is first embedded, the other prosthetic elements 2, 3 are embedded. As soon as the two corresponding clear centers (cap-like structure 9, recess 11) are arranged in the section S of the longitudinal axes L ₁ and L ₂ , the two prosthetic elements 2, 3 are separated by the cap-like structure 9 and the recess 11. They are connected to each other by means of the constructed joint 14. The intervertebral prosthesis 1 remains firmly in the prosthetic space because the intervertebral disc remains on the sides of the two prosthetic elements 2, 3 to join the cap-like structure 9 and the recess 11. The center of rotation is located in the central sagittal plane and can change forward or backward. The central sagittal plane passes through the patient's body and extends back and forth, intersecting the center of the body.

  Two transforaminal or extravertebral foramen access 12,13 are used for implantation and are known and established in spinal surgery. Once the connection is effective, the two prosthetic elements 2, 3 form a unit that recognizes the gradient of the endplates of adjacent vertebral bodies relative to each other.

  Due to the posterior implantation technique of the intervertebral prosthesis 1, the spinal ligament structure of the spinal column remains intact and the function of fixing the spinal column is not damaged. In addition, the intact spinal ligament structure reduces the risk of anterior movement of the intervertebral prosthesis 1 and the risk of endangering the spinal structure in the spinal column region. Similar techniques for surgical procedures are also applied anteriorly, especially in the board and thoracolumbar regions. Since access is blocked by the aorta and vena cava, the anatomical environment strictly eliminates anterior insertion. Also, in this case, the fibrous annular spine structure is maintained intact, as is the ligament of the front longitudinal member.

1 is a perspective view of an embodiment of an intervertebral prosthesis according to the present invention. FIG. It is a top view of the Example of the intervertebral prosthesis based on this invention shown in FIG. FIG. 3 is a plan view of the embodiment of the intervertebral prosthesis according to the present invention shown in FIG. 1, and is a view of a cross-section S similar to FIG. .

Claims (14)

An intervertebral prosthesis (1), in particular an intervertebral disc prosthesis with a central axis (6),
A) a first equivalence surface (4) in contact with an end plate of a first adjacent vertebral body disposed laterally of the central axis (6), and a first disposed laterally of the central axis (6). A first prosthetic element (2) having one internal surface (7) and a spherical recess (11);
B) a second equivalence surface (5) in contact with the end plate of the second adjacent vertebral body arranged transversely to the central axis (6) and a second arranged next to the central axis (6). A second prosthetic element (3) having a second inner surface (8) and a cap-like structure (9) corresponding to the recess (11),
C) The first and second prosthetic elements (2, 3) can be connected to articulated means by means of a cap structure (9) which slidably supports the recess 11;
D) The first and second prosthetic elements (2, 3) are arranged beside the central axis (6), have a width value of B and a length value of H, The first and second prosthetic elements (2, 3) each have a length H and a longitudinal axis L1 and a longitudinal axis L2 extending in parallel,
E) The length H is longer than the width B, and the first and second prosthetic elements (2, 3) are located in the intervertebral space and the two longitudinal axes L1 and L2 intersect. The angle α is α> 0 degrees,
F) An intervertebral prosthesis (1) in which the ratio of the length H to the width B is 3: 1 to 5: 1. One and hat-like structure of the first and second prosthetic components (2, 3) (9) is intervertebral prosthesis according to configured claim 1 from a component (1). The intervertebral prosthesis (1), the first and second prosthetic components (3) of one claim comprised of at least three parts of the hat-like structure made of detachable third part (9) 1 the intervertebral prosthesis according to (1). The intervertebral prosthesis (1) is composed of at least three parts and includes a joint shell, the shell including as a third part a recess detachable from the first and second prosthetic elements (2). the intervertebral prosthesis according to any one of 1 to 3 (1). The intervertebral prosthesis (1) according to claim 4 , wherein the cap-like structure (9) and the joint shell are made of a combined material of metal and plastic. The intervertebral prosthesis (1) according to claim 4 , wherein the cap-like structure (9) and the joint shell are composed of a combination of a plurality of ceramic materials. The intervertebral prosthesis (1) according to any one of claims 1 to 6, wherein the cap-like structure (9) and the surface of the recess (11) are covered with titanium carbide or amorphous carbon (ADLC). Hat like structure (9) is intervertebral prosthesis according to any one of constituted claims 1 to 7 at least the shape memory alloy (1). The intervertebral prosthesis (1) according to any one of claims 1 to 7, wherein at least the cap-like structure (9) is made of a substance having an expansion ability. The intervertebral prosthesis (1) according to any one of claims 1 to 7, wherein at least the cap-like structure (9) is made of a material having fluidity and thermosetting properties. The intervertebral prosthesis (1) according to claim 10 , wherein at least the cap-like structure (9) is composed of a monomer, a comonomer, a homopolymer, an oligomer, or a hybrid material comprising a material having fluidity and thermosetting properties. The thermosetting and flowable material is selected from the following group a) polyethylene glycol, preferably polyethylene glycol (di) -acrylate b) n-vinyl pyrrolidone c) vinyl, preferably vinyl alcohol d) styrene. 11. The intervertebral prosthesis (1) according to 11. It said first prosthetic component (2) is intervertebral prosthesis according to any one of claims 1 to 12 selected from the first kit of at least two first prosthetic component (2) (1) . It said second prosthetic component (2) is intervertebral prosthesis according to any one of claims 1 to 13 selected from the second kit of at least two second prosthetic components (2) (1) .

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